Chunk 21.0

## Summary This chunk details the implementation of a unified, budget-based memory manager for the cuzk CUDA ZK proving daemon, along with a lightweight HTTP JSON status API and an extended vast-manager HTML UI for live monitoring. The memory manager uses a budget system (400 GiB total) to gate memory allocation for synthesis and proving, with per-partition working memory of ~13.6 GiB for PoRep and ~8.6 GiB for SnapDeals. The status API exposes real-time pipeline state, GPU worker activity, memory usage, and counters, while the vast-manager UI polls this via SSH tunneling with ControlMaster reuse. Several bugs were fixed during live testing: a GPU worker state race condition (partition_gpu_end clobbering new job state), truncation of job IDs to 8 characters, and the synthesis max_concurrent display being changed from a static config parameter to a dynamic budget-based computation. A critical deployment issue was discovered—the remote machine uses an overlay filesystem where `/usr/local/bin/cuzk` cannot be replaced, requiring binaries to be deployed to `/data/` instead. The chunk also identifies a fundamental partition scheduling problem: all partitions from all jobs were dispatched as independent tokio tasks racing on a `Notify`-based budget acquire, causing thundering herd wakeups and random partition selection across pipelines. This resulted in all pipelines stalling together instead of completing sequentially. The fix implemented in the code (but not yet deployed/committed at the time of the chunk) replaces per-partition `tokio::spawn` with an ordered `mpsc::channel` and a synthesis worker pool that pulls FIFO, ensuring earlier jobs' partitions are processed before later ones. The code also includes a dynamic `synth_max` computation from the budget. The chunk ends with a clear list of next steps: deploy and test the ordered synthesis binary, run a proof to verify FIFO ordering, commit the changes, and address the port configuration mismatch between the daemon and vast-manager.

The Long Tail of Scheduling: From Budget Management to Priority Queues in the cuzk Proving Pipeline 2227 words

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